Microdialysis is an important research tool which enables detection and quantitative analysis of neurotransmitters. The technique can be particularly useful for research on brain disorders such as epilepsy and stroke. However, the current probes are relatively large and often result in significant injury to the brain tissue. Additionally, these probes require large quantities of dialysate, thus resulting in reduced sensitivity. This proposal addresses the challenges of miniaturization and sensitivity using both Micro Electro Mechanical Systems (MEMS) technology and a novel polymeric valve and a pump design. During Phase I, we will test the feasibility of using an electroactive polymer (polypyrrole) to actuate a novel pinch valve. Additionally, we propose to use polypyrrole to develop an ultra-low-flow peristaltic pump for transport of the dialysate without external instrumentation. Finally, we will couple these designs to a MEMS-based microfluidic channel system, and validate the technology in vitro. If successful, we envision a Phase II which includes the development and packaging of the MEMS microdialysis probe followed by in vivo testing in a rodent model of epilepsy. We believe that this will provide a useful specific device as well as to contribute to the development of versatile new microfluidic technology.